I have recently bought a mint F2AS from Japan and the installed a mint H2 screen I own. It's was absolutely wonderful before the start of my three week road trip, not a mark anywhere, but now there is dust inside, between the glass / fresnel. I see its an issue with these older cameras and a right pain in the *** to clean them.
Can I ask is the Beattie Nikon F Intenscreen one piece? If I could just get around this with a one piece screen, I would be happier. I have read all this stuff about using ultrasonic cleaners etc, but its not practical for the everyday photographer.